FAQs
13Aug13
Q: What is the tuning range of the loop?
As described, the loop tunes from approximately 2400-7800 kHz. Best performance is 60M and above.
Q: Can the tuning range be changed?
By adding turns turns or by increasing the size of the loop winding, the frequency range can be lowered, and vice versa.
Q: Can I get the schematics in .PNG or .GIF form?
They have been uploaded, and here is the link: http://www.mediafire.com/?5hmfdoqj03f6z8v
Q: Can this loop be used at higher frequencies?
Yes, my recollections tell me that I have made loops for up to around 18 MHz, with poor performance. But hindsight tells me that this was almost certainly due to the loops having poor loaded Q, and that it easy to fix. Such a loop would use the same amp and power supply as the loop detailed in the Package; only the winding needs to be different. I have run some numbers and have come up with the following as I would like to give one a try against 19 meter Euros:
The winding would be 2 circular turns of 1/4" soft copper refrigeration tubing, 14" in diameter, with a 3" gap between the turns. An appropriately sized frame could be built as described in the readme file in the Package, except that stubs for the wires would not be required. The tubing could simply be cable tied to the Tee and Cross fittings through a couple of holes.
The winding should have an inductance of about 2.1 uH, and the loop will have a projected tuning range of 6800 to 24000 kHz. Plus or minus.
Loaded Q at 15000 kHz should be around 735, giving a 3 dB BW of around 20 kHz. The Effective Height of this loop should be around 46 meters, and the absolute output and sensitivity of this loop should be very good. If the loop were made from 1/2" tubing, the loaded Q at 15000 kHz should be around 800, giving a 3 dB BW of around 18 kHz, and an Effective Height of around 51 meters.
In either case, the FOMP (ability of this loop to nuke local QRN) would be around 0.11, which is a very good figure. By comparison, at 15000 kHz the FOMP of a typical SML is about 0.24.
In the interests of accuracy and honesty, this question was a selfie...